1. Field of the Invention
The present invention relates to a metal mould dropping prevention device for use in a metal mould replacing system and, more specifically, to a device adapted to prevent a dropping of a metal mould placed on a metal mould replacing carriage or a metal mould depository stand from the carriage or the depository stand.
2. Description of Prior Art
Such a dropping prevention device known by the inventors of the present invention is the following one.
As shown in FIGS. 20 and 21, a stop lever 237 is supported swingably by a block 241 fixedly secured onto an upper surface of a metal mould depository stand 206. A stopper portion 242 is fixed to the upper end of the stop lever 237 while an actuating roller 244 is supported by a lower end thereof. A stop cancelling block 239 is fixedly secured to a side of a carriage 203 so as to face the roller 244.
Under such a condition that the stop lever 237 has been changed over to a downward posture ( refer to a solid line figure in FIG. 21 ), the stopper portion 242 is changed over to a projecting posture A. Thereby, a leftward movement of the metal mould 213 in FIG. 20 is blocked through its controlled portion 217, so that the metal mould 213 can be prevented from dropping from the depository stand 206. When the metal mould 213 is transferred from the depository stand 206 to the carriage 203, firstly the carriage 203 is moved rightward in FIG. 21 so as to displace the stop cancelling block 239 from the position indicated by the alternate long and two short dashes line to the position indicated by the alternate long and short dash line. Thereupon, the stop lever 237 swings ( refer to the figure indicated by the alternate long and short dash line ) so that the stopper portion 242 is changed over to a retracted posture B to fall in the stop cancelled condition. Thereby, the metal mould 213 becomes movable leftward in FIG. 20.
There is, however, a problem associated with the above-mentioned conventional embodiment.
In the case that many depository stands 206 are juxtaposed to one another in the left and right directions in FIG. 21, when the carriage 203 is moved to the location of the depository stand 206 for which the stop cancellation is going to be carried out, the stop cancelling block 239 cancels temporarily also stopped conditions of other stop levers 237, which stopped conditions are not required to be cancelled, on the way of movement of the carriage 203. It is apprehended that the metal moulds 213 under this condition would drop from the stands 206 when any shock might be imposed to those metal moulds 213.